Low-Power CMOS Synchronous Counter With Clock Gating Embedded Into Carry Propagation

A novel low-power CMOS synchronous counter whose clock-gating logic is embedded into a carry propagation circuit is proposed. The proposed synchronous counter operates with no redundant transitions and requires fewer transistors, minimizing the switching power consumption and silicon area as compared with conventional CMOS synchronous counters. The proposed synchronous counter consisting of 16 bits was fabricated in 0.18-mum CMOS technology. The experimental result indicates that the proposed synchronous counter achieves a power saving of 64% with 15% device count reduction.

I. Introduction

The asynchronous counter shown in Fig. 1 is one of the simplest but essential building blocks in very large scale integration design [1], [2]. It has been used for a long time in almost all electronic systems, including microprocessors, memories, communication devices, scientific instrumentation, and measurement systems [3]. for speeding up the counting operation of synchronous counters, a high-speed carry propagation circuit, such as a Manchester carry chain, has been used. Unfortunately, however, the operation of conventional synchronous counters is known to be very inefficient as far as the switching power consumption is concerned, since they have a lot of redundant transitions on internal switching nodes during counting operations [4], [5].